The difference between Apprehend and Arrest

Apprehend as a verb (transitive, archaic):

To take or seize; to take hold of.

Apprehend as a verb (transitive):

To take or seize (a person) by legal process; to arrest.

Apprehend as a verb (transitive):

To take hold of with the understanding, that is, to conceive in the mind; to become cognizant of; to understand; to recognize; to consider.

Apprehend as a verb (transitive):

To anticipate; especially, to anticipate with anxiety, dread, or fear; to fear.

Apprehend as a verb (intransitive):

To think, believe, or be of opinion; to understand; to suppose.

Apprehend as a verb (intransitive):

To be apprehensive; to fear.

Arrest as a noun:

A check, stop, an act or instance of arresting something.

Arrest as a noun:

The condition of being stopped, standstill.

Arrest as a noun (legal):

The process of arresting a criminal, suspect etc.

Arrest as a noun:

A confinement, detention, as after an arrest.

Arrest as a noun:

A device to physically arrest motion.

Arrest as a noun (nautical):

The judicial detention of a ship to secure a financial claim against its operators.

Arrest as a noun (obsolete):

Any seizure by power, physical or otherwise.

Arrest as a noun (farriery):

A scurfiness of the back part of the hind leg of a horse.

Arrest as a verb (obsolete, transitive):

To stop the motion of (a person or animal).

Arrest as a verb (obsolete, intransitive):

To stay, remain.

Arrest as a verb (transitive):

To stop or slow (a process, course etc.).

Arrest as a verb (transitive):

To seize (someone) with the authority of the law; to take into legal custody.

Arrest as a verb (transitive):

To catch the attention of.